1. Field of the Invention
The present invention relates to a detection device and a rotation angle sensor, and more particularly, to a detection device and a rotation angle sensor in which a substrate, on which a detection component for detecting the physical quantity, such as magnetism, is mounted, is held at a predetermined position in an outer case.
2. Description of the Related Art
In known electronic devices, such as hybrid ICs and various sensors, in which a substrate having elements mounted thereon is held in an outer case, the outer case is defined by a case body and a cover member attached to an opening of the case body, and the substrate is clamped between the case body and the cover member and is thereby held at a predetermined position in the outer case. For example, Japanese Unexamined Patent Application Publication No. H9-326567 discloses a resin-case fitting structure in which a printed board 61 is stored in a resin case 64 while being sandwiched between a body portion 62 and a cover portion 63 that define the resin case 64, as shown in FIG. 11. The body portion 62 includes ribs 65 each having an inclined portion 65a, and protuberances 66 for regulating the tilting of the printed board 61, and the cover portion 63 includes a projecting portion 67. The printed board 61 is pressed against the inclinations 65a by the projecting portion 67, so that the position of the printed board 61 is regulated in the resin case 64 by the protuberances 66 and the inclinations 65a. 
In the above-described printed-board fixing structure, when the cover member 63 is fitted on the body portion 62, the printed board 61 is similarly fixed to the resin case 64. Therefore, assembly is easy and assembly efficiency is high. Unfortunately, there are the following problems. That is, as shown in FIG. 12, when it is assumed that D represents the distance between leading ends of the protuberances 66 of the body portion 62 and a leading end of the projecting portion 67 of the cover portion 63 and T represents the thickness of the printed board 61 in a state in which the cover portion 63 is fixed to the body portion 62, the printed board 61 is clamped between the protuberances 66 and the projecting portion 67 on the condition that D≦T. In this case, the bending amount of the printed board 61 is equal to T−D. The distance D has an value α based on dimensional variations of the body portion 62, the cover portion 63, the protuberances 66, and the projecting portion 67. For this reason, the distance D needs to be decreased by the value α or more in order for the printed board 61 to be clamped between the protuberances 66 and the projecting portion 67.
However, when the distance D between the leading ends of the protuberances 66 and the leading end of the projecting portion 67 decreases, the bending amount T−D of the printed board 61 increases. This increases the bending stress of the printed board 61, and also increases breaking, peeling, and soldering cracks of patterns on the printed board 61. Further, when the dimensional accuracy of the body portion 62 and the cover portion 63 is increased and the value α is decreased in order to reduce the bending stress of the printed board 61, the production cost is increased.